The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Elderly people need newer cars: study

Elderly people are getting injured because they are holding on to their cars for too long, the NRMA says.

A new study has found senior citizens can significantly reduce the chance of injuring themselves in car accidents by upgrading their vehicles.

Figures from the study, released by insurance company NRMA and the NSW Centre for Road Safety on Thursday, showed the safety of older drivers in NSW was strongly linked to their choice of car.

"Injuries to older drivers could be reduced by 90 per cent if they upgraded to the safest vehicle available currently for sale in Australia," the study said.

The risk of serious injury would drop 37 per cent by purchasing "an affordable Australian model built after 2000," it said.

Because the elderly tend to retain their cars for longer, they are more at risk as safety features in older models are less effective than those in newer cars, NSW Centre for Road Safety manager Marg Prendergast said.

"The fact that older drivers retain their vehicles for longer may be due to budgetary constraints, resistance to adapting to a new vehicle or an assumption that their current vehicle is safe," she said.

"They also tend to choose smaller vehicles, which may put them at a disadvantage in two-vehicle crashes, a particular problem for older drivers who are over represented in multi-vehicle crashes," she said.